When an elevator is reformed, a part of or all of devices thereof are replaced. In addition, unnecessary devices are removed and necessary devices are newly added. Performing such work requires accurate dimensional data on a current shaft. For example, when there is not enough space to install a new device, to what extent a wall of the shaft needs to be scraped off has to be determined on the basis of the dimensional data.
Patent Literature 1 describes a system for measuring dimensions of a shaft. The system described in Patent Literature 1 includes a laser range finder. The laser range finder is provided on an elevator car. With the laser range finder, a distance to a wall of the shaft is measured while the car moves.